The railroad industry has long been plagued by the problem of loose rails along the roadbeds. Although the rails are secured to cross-ties by driving headed spikes into the ties to contact the flanges of the rails, loose rails may still result from several factors. First, the movement of the railroad engine and loaded cars along the rails produces a wave-like motion in the rails. This motion in unavoidable because railroad engines and cars are extremely heavy and their weight is concentrated on a very small area under each wheel at the rail. As a result, as a loaded train moves along the rail, a particular point on the rail will be alternately subjected to an extremely high load when a wheel is directly on that spot, followed by a period when that spot is subjected to no load when it is between the wheels of the train. This wave-like loading pattern produces an undulating force which tends to pull the spike loose from its tight fitting position between the flange of the rail and the tie. The upward force on the head of the spike eventually causes it to back out of the hole in the tie. This creates a situation in which the rail is free to move somewhat in a vertical plane in response to the wave motion. This looseness further compounds the problem since the rail now is free to undulate even more as the load of a moving train progresses down its length. This undulation exaggerates the force, creating an upward pull on the head of the spike. Eventually, sufficient looseness results that the hazard of derailment is created because of the degree of movement permitted by the loose spike.
In addition to the effects of the rolling load along the rail, spikes are subjected to a lifting force because of variations in the roadbed. Heaving in the roadbed due to freezing conditions or because of drainage problems creates uneven support beneath the cross ties. This permits one rail or the other to shift out of alignment with the opposite rail. Because both rails are no longer in the same horizontal plane, a moving railroad locomotive and its loaded cars will sway from side to side as it passes the misaligned region of the rails. This swaying movement exerts an outward force on the spike holding each rail. The lateral force on the top of the rail tends to rock the rail or cause it to rotate about its base flange. This rocking motion of the rail tends to lift the head of the spike which is positioned over the top of the outside web of the rail flange.
Early attempts to solve this problem resulted in the use of threaded spikes which were twisted into the wooden tie and positioned to hold down the rail. This solution introduced significant expense in laying a roadbed because of the greater labor involved in inserting a threaded spike as opposed to a driven spike. Not only that, the solution was not particularly effective because a secondary problem was introduced. Threaded spikes produced a very tight connection between the components of the railbed. Although at first glance, this would seem to be a beneficial arrangement, it in fact is a very unsatisfactory arrangement. Because of the exceptionally high loads encountered with a rolling railroad engine and its load, the connection at the spike must be somewhat resilient or flexible. If this connection is rigid, the effects of the load are concentrated at the head of the spike and produce working stresses that eventually cause the fracture of the spike and the complete loosening of the rail.
It is therefore an object of my invention to produce a secure, yet resilient retainer for a railroad spike.
Another solution to the problem of loosening railroad spikes has been the use of a locking insert placed between the spike and the tie. Such methods or apparatus were disclosed in the following United States patents:
Inventor Date Patent Number ______________________________________ W. D. Forsyth Aug. 13, 1907 862,898 G. B. Cutting Feb. 18, 1919 1,294,778 G. B. Cutting Apr. 3, 1923 1,450,280 R. D. Wagner Apr. 26, 1932 1,855,329 H. T. Jones Oct. 4, 1955 2,719,452 N. K. Moses June 29, 1965 3,191,864 ______________________________________
Each of the above references provided means for securing the insert to the tie. However, none of the disclosed methods or apparatus produced any locking or retaining force on the spike itself. The possible exception to this is the alternative structure disclosed by the Wagner reference. However, the alternative structure disclosed by the Wagner reference, as well as the Jones reference, require the use of specially shaped spikes. Because these references require the use of special spikes, the apparatus of both references would be inapplicable to presently designed spikes and would create problems of inventory, compatibility and interchangeability with the existing roadbed apparatus.
Therefore, it is another object of my invention to provide a railroad spike retainer which applies a restraining force to the spike in excess of a frictional force.
It is yet another object of my invention to provide a railroad spike retainer which is effective to restrain spikes of standard configuration.
An additional problem arises in the use of any of the above cited patents. Each of the disclosed inserts must be separately inserted into a hole. As a result, a separate hole drilling operation must be undertaken, followed by the insertion of the retaining insert, after which the spike can be driven into the insert. The extra operations of drilling the hole and placing an insert in the drilled hole increases significantly the labor involved in putting down the roadbed compared with the cost of producing such a roadbed using driven spikes.
It is a further object of my invention to provide a railroad spike retainer which may be positioned simultaneously with the driving of the spike to be retained into the tie.
These and other objects and features of my invention can be more readily understood by reading the following detailed description in conjunction with the drawing.